1915.] NATURAL SCIENCES OF PHILADELPHIA. 293 THE GENUS GRYLLUS (ORTHOPTERA) AS FOUND IN AMERICA. BY JAMES A. G. REHN AND MORGAN HEBARD. To the systematic orthopterlst, the crickets of the genus Gryllus have proven to be one of the greatest stumbHng-blocks in the order. This is true of the forms found in both hemispheres, but this assertion has especial emphasis when the American forms alone are considered. This is not due to a lack of study, as Scudder and Blatchley have in recent years both endeavored to diagnose certain or all of at least the North American species, using what might be called "conventional" morphological characters, while Lutz, approaching the subject from a biometric point of view, concludes that species in an anyway natural sense do not exist in the genus, in this skepticism representing the other extreme from Scudder, who categorically defines a number of species. The present authors have been unable in the past to approach the subject with sufficient material to enable them to do more than endeavor to assign certain of their series to various of the forms recognized by Scudder. There has been constant and increasing difficulty in doing this, as, while some individuals would fit certain of the specific descriptions, others would be found agreeing in various features with two or more of the specific diagnoses, the sum total of almost any representation showing an endless complexity of the characters used to differentiate the numerous described forms. The fact is quickly recognizable that almost all of the descriptions of these species were chiefly concerned with size, coloration (not color pattern), venation (in number of transverse (oblique of Saussure) veins in the male tegmen and number of branches of the mediastine vein in both sexes), tegminal length, degree of development of wings and ovipositor length. Such factors have been found to be of minor importance or of no specific value whatsoever in certain other related genera, and the natural uncertainty of the status of the American forms has led us to undertake a more searching study of these. This work is based on all of the American material of the genus before us, 1,504 specimens. The results explain to our complete satisfaction the reasons for the past confusion, a summarj^ of which is given below.